This invention relates to improvements relating to cameras. In particular, it relates to methods of estimating the heading angle of a camera system associated with a vehicle, a method of improving the accuracy of such a camera system and apparatus for performing the methods. As used in the following description the term “heading angle” is to mean “angle of the direction of movement vector with respect to a vehicle longitudinal axis”.
It is known to provide camera systems for vehicles, which capture images of objects and features on the road. A processor may then determine the position of the objects in the image relative to the vehicle. Typically, vehicle-based camera systems are used for lane or vehicle detection. It is known that, to function correctly, the alignment of the camera relative to the vehicle must be known. For an example, for a forward facing camera, an error of 0.6° in the camera yaw will lead to an error of 1 meter in the calculation of the lateral position of an object visible in the image at 100 meters distance from the vehicle. Even with careful aliment and positioning of the camera, it is still possible for a small error to exist. The camera may also become misaligned over time during use of the vehicle.